The Institute of Electrical and Electronics Engineers (IEEE) has adopted a series of standards for both wireless local area networks (WLANs) known as 802.11 and wireless metropolitan area networks (WMANs) known as 802.16. It is commonly known that WiFi refers to interoperable implementations of the IEEE 802.11 technology, and WiMAX (worldwide interoperability for microwave access) refers to interoperable implementations of the IEEE 802.16 technology. On the other hand, Bluetooth is a wireless standard for wireless personal area networks (WPANs) developed by the Bluetooth special interest group (SIG). Bluetooth provides a secure way for exchanging data over short distances using frequency-hopping spread spectrum technology. Due to scarce radio spectrum resource, different technologies may operate in overlapping or adjacent radio spectrums. For example, WiFi often operates at 2.412-2.4835 GHz, WiMAX often operates at 2.3-2.4 or 2.496-2.690 GHz, and Bluetooth often operates at 2.402-2.480 GHz.
As the demand for wireless communication continues to increase, wireless communication devices such as cellular telephones, personal digital assistants (PDAs), laptop computers, etc., are increasingly being equipped with multiple radios. A multiple radio terminal (MRT) may simultaneously include Bluetooth, WiMAX, and WiFi radios. Simultaneous operation of multiple radio modules co-located on the same physical device, however, can suffer significant degradation including significant interference between them because of the overlapping or adjacent radio spectrums. Due to physical proximity and radio power leakage, when the transmission of data for a first radio module overlaps with the reception of data for a second radio module in time domain, the second radio module reception can suffer due to interference from the first radio module transmission. Likewise, data transmission of the second radio module can interfere with data reception of the first radio module.
FIG. 1 (Prior Art) is a diagram that illustrates interference between a mobile wireless system (MWS) radio module 11 and a Bluetooth (BT) master radio module 12 that are co-located in an MRT10. Both MWS11 and BT12 transmit and receive data via scheduled transmitting (TX) and receiving (RX) time slots on a frame-by-frame basis. For example, each MWS frame contains five consecutive RX slots scheduled for receiving operation followed by three consecutive TX slots scheduled for transmitting operation. On the other hand, a Time Division Duplex (TDD) scheme is used by BT devices where a BT master and a BT slave alternate TX and RX operation. Because MWS radio module 11 and BT radio module 12 are co-located within MRT10, in a general, the transmission of one radio module will interfere with the reception of another radio module. As illustrated in FIG. 1, data reception in three RX time slots of BT12 are interfered by concurrent data transmission in TX time slots of MWS11, and data reception in six RX time slots of MWS11 are interfered by concurrent data transmission in TX time slots of BT12.
FIG. 2 (Prior Art) is a diagram that illustrates traffic pattern of a BT master device 22 affected by a co-located MWS radio module 21. The traffic pattern of MWS21 remains the same as the traffic pattern of MWS11 in FIG. 1, while BT22 has an Extended Voice (EV3) traffic pattern using an Extended Synchronous Connection Oriented (eSCO) link, with TeSCO=6 and WeSCO=4. Under such EV3 traffic pattern, BT22 has one scheduled TX time slot followed by one scheduled RX time slot for every six BT slots (i.e., TeSCO=6), with four retransmission opportunities (i.e., WeSCO=4). In the example of FIG. 2, data transmission of MWS21 interferes with data reception of BT22, while data transmission of BT22 does not interfere with data reception of MWS21 (e.g., because of low transmission power of BT22). As a result, EV3 data reception in the scheduled EV3RX time slot in eSCO window #2 is corrupted, causing BT22 to re-transmit EV3 data to a BT slave in the following EV3TX time slot and to receive EV3 data from the BT slave in the following EV3RX time slot successfully. It can be seen that BT22 consumes 25% more energy due to interference from co-located MWS21. A solution is sought to improve efficiency and save energy for radio modules co-located within the same MRT.